Probe Dependent Solvation Dynamics Study in a Microscopically Immiscible Dimethyl Sulfoxide–Glycerol Binary Solvent

Abstract

Excited state dipole solvation of three coumarin dyes with different hydrophobicities was studied in DMSO-glycerol binary solvent. The solvation times obtained from the three dyes are remarkably different. The highly hydrophilic dye coumarin 343 (C343) exhibits the slowest solvation time (>12 ns) among all the dyes we used. This is in contrast to the most hydrophobic dye coumarin 153 (C153), where the solvated state is reached just within ∼104 ps. However, the moderately hydrophobic dye coumarin 480 (C480) demonstrates an intermediate (∼396 ps) solvation time. Unprecedented slowdown of solvation time of C343 is probably due to the slow diffusion of solvent molecules in the glycerol-rich first solvation shell followed by hydrogen bond rearrangements around the solute dipole. On the other hand, fast solvation of hydrophobic dye C153 is most likely caused by the fast reorganization dynamics of hydrophobic -CH groups of DMSO or the carbon backbone of the glycerol molecule around the solute dipole. Interestingly, a remarkable probe dependency in solvation dynamics was not observed in the case of DMSO-water binary solvent or in a neat solvent isopropanol. Probe dependent solvation in a DMSO-glycerol mixture is attributed to the microscopic phase segregation and different locations of coumarin dyes within this binary solvent.

Ultrafast Dynamics of a Fluorescent Tetrazolium Compound in Solution

“…With deep-UVe xcitation, also ah igher lying electronic state is reached, but the emission spectra in Figure 1b impart relaxation to the lowest lying excited state for both UV wavelengths. [80,81] The value of t 2 = 204 ps found for PTCi ng lycerol might correspond to these observations. The involvement of solvation can be inferred from the TCSPC data in the viscouss olvents ethylene glycol and glycerolw here af urther component (t 2 in Ta ble 1) had to be included for satisfactorily fitting the data.…”

Study of Microheterogeneity in Acetonitrile–Water Binary Mixtures by using Polarity‐Resolved Solvation Dynamics

“…Huppert and co‐workers observed a high Z value (≈1.7) in the hexane–propionitrile binary mixtures, which they explained by considering the diffusion of polar propionitrile molecules into the first solvation shell of the coumarin 153 (C153) dipole . Solvation dynamics in a binary solvent has emerged as an important subject in several experimental and theoretical studies over the last few decades . The dynamic features in a binary solvent, in most of the cases, are perturbed by solvent cluster formation, structural fluctuations, conformational changes of the complexes formed by solvent molecules, and solvent‐network formation .…”

Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals

“…In this procedure, TRES of C153 at a particular time is constructed from steady state emission spectrum and lifetimes at different emission wavelengths of the dye molecule dissolved in LCs. A more detail of TRES construction procedure and theoretical approaches can be found in several literatures . We plotted the time evolution of solvent correlation function [C(t)] using emission energies at different times.…”

“…Rotational anisotropy decay provides an estimation of the rotational diffusion time of the excited solute dipole within the solvent medium. A detail of measurement techniques, fittings and instrumental part for rotational anisotropy measurement can be found elsewhere . In 1926, Perrin correlated the anisotropy with rotational diffusion process responsible for depolarization of the emitting light using the following equation…”